The present invention relates to implantable medical devices and more particularly to a tool for use in surgically implanting such devices. A common role for such an implantable device is nerve or muscle stimulation and more particularly Spinal Cord Stimulation (SCS). SCS systems typically include an implantable pulse generator (IPG) which is a source of stimulation current, and an implantable electrode array, which provides the stimulation current to the nerves to be stimulated. In many cases where such devices are utilized, the electrode array is remote from the location of the IPG. In such cases, an electrode lead extension is used to connect the IPG to the electrode array. For example, in the case of spinal cord stimulation, the electrodes providing the stimulation current to the nerves must be positioned adjacent to the spinal cord, but sufficient space is not available for the IPG in the area adjacent to the electrodes. In this example, the IPG must be located remotely from the electrode array and a tunneling tool is required to first create a subcutaneous tunnel from the location of the electrode lead to the location of the IPG, and then to carry the electrode lead extension back through the tunnel to the electrode lead.
Existing subcutaneous tunneling and carrying tools require a separate tunneling tip and carrying tip. After the tunnel is created using the tunneling tip, the tunneling tip must be removed and the carrying tip attached. The common method of attachment is a threaded adapter on the end of a shaft. This approach requires that the tunneling tip be removed by unscrewing and the carrying tip be attached similarly. The requirement to unscrew one tip and screw on another tip adds to the complexity of the surgical procedure. If the threads are damaged in the process of installing the carrier, a new tunneling tool and/or carrier must be used. The need to keep surgical procedures as simple and error free as possible dictates that a more robust approach be found.
The present invention advantageously addresses the above and other needs by providing an integrated subcutaneous tunneling and carrying tool, functionally similar to existing tools, that eliminates the need to unscrew a tunneling tip and screw on a separate carrying tip. The tool provided by the present invention is used to create a tunnel through body tissue, and then to carry an electrode lead extension through the tunnel for connection to the electrode lead, without requiring the manipulation of threaded tips. The electrode lead extension includes a female lead extension connector which connects with a male connector on the end of the electrode lead. A tool according to the present invention includes either a cavity that the lead extension connector is inserted into, a male connector similar to the connector on the electrode lead, which male connector is connected to the lead extension connector, or a second male connector, which second connector connects to a disposable carrier which the lead extension connector is carried in. At least four embodiments of the present invention are envisioned.
In a first embodiment of the integrated subcutaneous tunneling and carrying tool, a carrier is employed that serves both the function of tunneling and carrying. After the tool has completed the tunneling process, a cover that is part of the carrier is opened by a simple pull and twist action, and the lead extension connector is inserted into the carrier. Then, the tool is pulled back through the tunnel, carrying the lead extension connector and attached electrode lead extension.
In a second embodiment, the integrated subcutaneous tunneling and carrying tool includes a mating connector designed to connect with the lead extension connector and attached electrode lead extension. The mating connector is the same basic shape as the corresponding male connector on the electrode lead to which the lead extension connector attaches, and also has a tip suitable for tunneling. After creating the tunnel and connecting the lead extension connector, the tool is pulled back through the tunnel, pulling the electrode lead extension with it. In this embodiment, the section of the tool adjacent to the mating connector may be enlarged to provide additional clearance for pulling the lead extension connector and electrode lead extension through the tunnel.
In a third embodiment, the lead extension connector of the electrode lead extension is delivered packaged in a disposable carrier. The disposable carrier includes a receptacle with an attaching mechanism. The integrated subcutaneous tunneling and carrying tool includes a mating connector designed to both tunnel and to engage the attaching mechanism of the disposable carrier. After the tunneling tool is pushed through the tissue, the disposable carrier is attached to the mating connector and then pulled back through the tunnel. After the carrier is pulled through the tunnel, the lead extension connector is removed, And the disposable carrier is discarded.
In a fourth embodiment, the tool includes a carrier permanently attached to the tool. The carrier comprises a carrier body and a carrier cover, which carrier cover has a pointed end for tunneling. After the tunnel has been made, the cover is removed and discarded. The lead extension connector is inserted into a cavity in the carrier body, and the electrode lead extension is pulled back through the tunnel.
It is thus a feature of the present invention to provide several embodiments embodiments of a simple-to-use tool, which provides a tunneling capability, and a carrying capability, without difficult manipulation of tool components.